title: Ozonation degrades all detectable organic compound classes in oil sands process-affected water; an application of high-performance liquid chromatography/obitrap mass spectrometry.
abstract: BACKGROUND
  Surface mining of bitumen in Northern Alberta, Canada, results in large volumes of toxic oil sands process-affected water (OSPW) that must be contained in tailings ponds. Ozonation has shown great promise as an OSPW treatment process, by decreasing its toxicity and increasing its biodegradability, but the effect of ozonation on the thousands of dissolved organic chemical groups has not yet been examined.
  
  
  METHODS
  Reversed-phase liquid chromatography with ultrahigh-resolution linear ion trap-orbitrap mass spectrometry was applied to the characterization of treated (utilized ozone doses of 20 and 50 mg O3/L) and untreated OSPW. The analysis was performed in positive and negative electrospray ionization modes for each sample (ESI(+)/ESI(-)).
  
  
  RESULTS
  Semi-quantitative analysis of ozonated and unozonated samples allowed degradation to be monitored for naphthenic acids (i.e. O2 species in ESI(-) mode) and >2000 other organic species belonging to various heteroatom-containing classes: Ox (where x = 1 to 6), NOx (where x = 1 to 4), SOx (where x = 1 to 4), NO2 S, N, and S. No chlorinated byproducts were detected in any treated sample, but at the low dose (20 mg O3/L) some compound classes increased in abundance (e.g. the O5 class), indicating that they were formed as byproducts at faster rates than they were degraded. Nevertheless, all organic compound classes subsequently diminished at the higher dose (50 mg O3/L). For several Ox and SOx classes, species observed in ESI(+) mode (e.g. O2(+) species) were often more recalcitrant to ozonation than the corresponding species detected in ESI(-) mode (e.g. O2(-) species; naphthenic acids).
  
  
  CONCLUSIONS
  Ozonation appears to be a very suitable treatment option for OSPW, but the more recalcitrant groups of compounds may help to explain the residual toxicity of ozonated OSPW. Analysis of OSPW constituents in both ionization modes is warranted in all future OSPW fate studies.
authors.affiliation: Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, T6G 2G3, Canada.
authors.forename: Alberto S
authors.initials: AS
authors.lastname: Pereira
authors.forename: Md Shahinoor
authors.initials: MS
authors.lastname: Islam
authors.forename: Mohamed Gamal
authors.initials: MG
authors.lastname: El-Din
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Martin
mesh_terms: D056148:Chromatography, Reverse-Phase; D013058:Mass Spectrometry; D061329:Oil and Gas Fields / Q000737:chemistry*; D009930:Organic Chemicals / Q000302:isolation & purification*; D010126:Ozone / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D010126:Ozone